The trackpad of my Macbook Pro works for moving cursor but not for clicking! Help!

I came back home and my husband said the computer was working. he says he didnt do anything to it. But the trackpad works for moving the cursor, but when I click something I heard the sound but the clicking command is not working. I am able to move over windows, etc but cant click or choose anything. This has never happen before, I already and I am sure no water was spilled on it. How do I make the clicking of the trackpad work?!!!! Its driving me crazy! I am right now using my extra laptop (not mac) but I need my mac to do my homework, thats where my stuff is....Help!!!!